The spread of the virus slowed over the weekend but the respite might only be brief, experts have warned. More than 200,000 computers have been affected so far.

“We have seen vulnerabilities stored by the CIA show up on WikiLeaks, and now this vulnerability stolen from the US military intelligence organisation National Security Agency (NSA) has affected customers around the world,” Smith wrote.

“An equivalent scenario with conventional weapons would be the US military having some of its Tomahawk missiles stolen.”

The Microsoft President also added: “The governments of the world should treat this attack as a wake-up call.”

Microsoft said it had released a Windows security update in March to tackle the problem involved in the latest attack, but many users were yet to run it.

“As cybercriminals become more sophisticated, there is simply no way for customers to protect themselves against threats unless they update their systems,” BBC quoted Smith as saying.